1. Field of the Invention
The present invention relates to a pulse cleaning filter system arrangement, which is especially applicable for the air intake of a gas turbine or a combustion turbine.
2. Description of the Related Art
The operation of a gas turbine or a combustion turbine requires the ingestion of a large volume of ambient air. Filtration of the ambient air by using an inlet filter system is required in order to protect the gas turbine or the combustion turbine from the negative effects of contaminated air, which include foreign object damage, erosion, and turbine blade fouling.
Generally, an inlet filter system comprises a housing with a tubesheet that separates the inlet side and the outlet side of the housing. The tubesheet comprises multiple tubesheet openings, each of which is associated with a filter cartridge. The filter cartridges have an open end sealed around the respective tubesheet opening and a closed end at the inlet side of the housing. The filter cartridges are usually conical or cylindrical cartridges, or combinations of these.
As a result of introducing an ambient air stream through the inlet filter system, particulate matter collects on the filter cartridges and tends to increase the flow resistance of the filter system. Occasionally, the filters need to be replaced, but more preferably, the filters are cleaned by using, for example, a reverse gas pulse cleaning approach. In the reverse gas pulse cleaning approach, gas pulses, typically, air pulses, are introduced periodically against the direction of the normal air stream through the tubesheet openings into the filter cartridges. The gas pulses remove particulate matter collected on the inlet surfaces of the filter cartridges, which tends to reduce the flow resistance of the filter system.
U.S. Pat. No. 7,195,659 B2 discloses a pulse cleaning filter system arrangement comprising a vertical compressed air header arranged at the inlet side of a vertical tubesheet, between V-style filter elements, and multiple immersion type pulse valves arranged one on top of the other in the air header. Each of the valves provides the ability to allow air pulses to flow along a blowpipe to the outlet side of the tubesheet and, after two slanted rectangular bends, via a nozzle through a tubesheet opening to the outlet surface of a filter element. The immersion style pulse headers are relatively expensive to fabricate and to install. The immersion type headers have the drawback of the internal blowpipes reducing the free volume available for the compressed air to be stored in the air header.
U.S. Patent Application Publication No. 2008/0022856 A1, issued as U.S. Pat. No. 7,585,343 B2 on Sep. 8, 2009, discloses a pulse cleaning filter system arrangement differing from that disclosed in U.S. Pat. No. 7,195,659 B2, in that relatively long two-piece filter cartridge pairs are used, and in that the one on top of the other arranged blowpipes are bent to extend as horizontal pipe sections at the outlet side of a tubesheet. The horizontal pipe sections cross with central axes of two adjacent filter element pairs, and air nozzles are arranged in the crossings so as to inject air pulses to the respective filter element pairs. The arrangement has the same weaknesses as the one described above. Moreover, bending and installing of the blowpipes is relatively complicated due to an additional bend required, in addition to a slanted ninety degree bend, for the alignment of the horizontal pipe sections at the outlet side of a tubesheet. The additional bend also increases the pressure drop of the air pulses, and thus limits the filter cleaning capacity. Utilizing long two-piece filter cartridge pairs limits the number of cartridges that can be effectively cleaned by a single pulse valve.
An object of the invention is to provide a simple pulse cleaning filter system arrangement in which at least some of the disadvantages of the prior art are minimized.